Air cleaner for gas engine intakes



Oct. 29, 1935.

H.IF. WEISS 2,019,241 AIR cmmmn FOR GAS ENGINE 'mmxss Filed Aug. 15,1933 Z'Sheets-Sheet 1 INVENTOR h. I. We/ss.

BY BW IUaM/IAL vdzam ATTORNEYS AIR CLEANER FOR GAS ENGINE INTAKES FiledAug. 15, 1933 2 Sheets-Sheet 2 INVENTOR I?! A IVs/'5 s BY WW 16m my.154m.

' ATTORNEYS Patented Oct. 29, 1935 UNITED STATES sm was GAS 1' Howard F.Weiss, mama-winning we; r. Burgess laboratories, Inc., Madison, Wits-Yacorporation ofDelaware I Application August 15. at,"

Is (mesa,

This invention relates to an air filtering medium, particularly to afiltering mass-to be used as an air cleaner for an automobilecarburetor. It also relates to a filtering unit for such use. 5 It is anobject of the invention to provide a filtering mass which possesses highfiltering efli-' ciency without ofiering excessive resistance to theflow of air therethrough. It is a further object of the invention topro- 10 vide a filtering mass which maintains its high efficiencythroughout a long period of usefulness.

It is a further object of the invention to provide an efiicientfiltering mass which is light in weight and inexpensive and which isadapted to 15 be adiusted to meet diiferent service conditions withuniform eifectiveness.

The filtering medium of this invention comprises a gas pervious mass ofmatted, intertangled, elongated strands providing among them alabygorinth or maze of interstices through which the air or gas to befiltered is conducted. The filtering materials of this general characterwhich have been used heretofore possess various disadvantages, such aslow filtering emciency; rapid .de- 5 crease in filtering efficiencyafter short periods of use, increased cost, uneven matting down with useto provide open channels with no filtering eifect and breakage of thefibers, with the passage of fragments into the motor.

This invention provides a filtering mass is relatively inexpensive andis substantially free of most ofthe disadvantages mentioned, Theelongatedstrands ofthis invention are formed from billets of wood. Theyare cut by-means of 3'5 knives which move longitudinally 01 the woodbilv lets, substantially parallel to the grain, and produce relativelyflat-sided-strands, angular in cross-section. The knives do notperform-a smooth cutting operation but act somewhat as 40 advancingwedges with the result that the strands are partially cut and partiallytorn from the 55? substantially permanently. While the breakage of me lc 1 W610! 1 m mentsinto thefmoto f e'sult-in seriousabrasionjandscorin'zioftiiovig parts-"i passage of wood 'frasmentsther'einto-produces nosuch "ill 'ln'thevd'rawines iv j v 1 is enlargedside view of'a fragment of a wood strand suitable for use 3 in 'my r vsdl i s :i-.-

2 is an enlarged lend1viewof the strand showninFigl; I r

- 3 'is-a'detail view-showing the way in which 'the' .fcavity of. a;Wood.' ;fiberl is exposed in the surface'ofia. wood strand;

rig. 4 is a side vjiew'of' one in 621' filtering unit bmprising a.formed" ma the Strands illustratedinFigalandm ,5 is atop view of. theunit shown in Fig.4;

6 is a verticalx'sectional view of a similar flltering unit in whichthemassfis retained within a frame. whichis mounted in an air cleanerbody;

Fig. '1 tea horlz' ontalsectional' view' or the unit Figs'.-8-and 9 are.horizontal sectional views. of

modifications 'of the ume'shown in Figab and 7.

.Incar'ryingout invention, 1 find it advantasao o u e mu n ci s of w s,M a elm, fash, bas wmd,..pop1ar, etc. "with some species, such asash,;-cypress, basswood. etc;, 80 the flurfwes of the 'stran e1rough rand have a greater proportioniof "and-jagged fragments or.flbers'project'ing efromQ'than with r p ie Forth "'urposeeof minimizingthe weight of thefilteringmass'jthe less dense species 85 may 'be used.f "Since density varies inversely with "P r i y, "the more porous-jwoods are" also the lighter woods;

I The strand 10- shown in 1 and 2 is formed from basswood and exhibitsthe rough and jagged 40 surfaces produced 'bythe process of itsformation. Series of-groovesjll and'ridges I! are produced in thestrand.similar," on a smaller scale, to thoseseen-upon the surfaces of woodthat has been split. withjan axe; ,At numerous places along .ithe lengthof. strand Ill portions I3 .01 the woodjaretornlooseand project from thesurface. A-projection l3, may be a single wood fiber. or a-bundleor'fibers. Upon the surfaces of some of'fthe,projections l.3, and alsoat points upon the surface of thestrand, there are fringes M ofgauze-likecharacter, ,composed ,of minute hairlike particles of wood .ofmicroscopic" size. Projections l3 and fringes areimportant factors in myinvention. 2 th'e open-p res I 5 which may be the cell-cavities ofindividual wood fibers or the continuous sap-conducting vessels whichextend longitudinally of the strand. The cutting operation exposes thelongitudinal sections of some of the pores, which appear under themicroscope in the form of elongated deep fissures. While the cuttingknife moves. substantially parallel to the grain of the wood, it doesnot follow the grain exactly with the result that a proportion of thefibers are severed transversely, exposing the open pores upon thesurface of the strand. This is illustrated in Fig. 3 wherein itrepresents the surface of the strand, l8 an individual fiber and H theexposed cavity. The diagonal lines surrounding the fiber 18 representthe other fibers which go to make up the strand. Others are exposed bythe rupturing of the fibers caused by the tearing action describedheretofore. The strand does not have an epidermis and is preferred overother organic materials for that reason, since an epidermis seals overthe pores and provides a more or less smooth surface. In fact, thesurface roughness of the wood strands may be enhanced by subjecting themto a mechanical rubbing operation. This is more effective if the strandsare soaked in water prior to or during the operation after which theymay be dried again. The roughness may also be increased by treating thestrands with a solution of a caustic alkali.

The strands are preferably ribbon-like, that is, their transverse shapeis such that one side is thin with respect to the other. Fig. 2illustrates the flattened transverse shape. The preferred transversedimensions are, thickness, about 0.005 to 0.015, width, about 0.020 to0.050 inch. The length should not be less than one-half inch, and shouldpreferably be more than three inches.

To form the filtering medium, a mass of the strands is packed or waddedtogether in heterogeneous manner, care being taken that the density ofpacking is maintained substantially uniform throughout. There is thusprovided a system of uniformly distributed, intercommunicating voids.The mass may be maintained in its form by a frame, as will be describedhereinafter. A treatment with a viscous substance, such as oil, may beapplied thereto. The mass of wood strands, either with or without theviscous coating, successfully resists any heat or fire which may becaused by back-firing of the engine. As stated heretofore, an adhesivemay be applied to the strands to prevent uneven matting down of the masswith use. This may be done before or after the mass is formed; byimmersing the strands in the adhesive or by spraying the adhesive uponthem. If the strands are immersed in the adhesive the proportion ofadhesive may be regulated by centrifuging the excess oif of the strands.

A wide variety of adhesives may be used, such a casein glue, bloodalbumen glue, starch glue,

.etc., but it is preferred to use an adhesive having, as a base, analkali silicate such as sodium silicate. An aqueous solution containingabout 40% solids is used.

Sufficient adhesive is applied to the strands to bind them together infixed form and relation. About three to six parts by weight of silicatesolution is used to one part of wood. After the binder has dried thereare'approximately 1%, to 2 parts of binder present to one part of wood,but due to the much greater density of the binder, the volume proportionof the latter is compara tively small. It binds the strands togetherwhere they join and forms only a thin and discontinuous coating upon therest of the strands surfaces. The surface roughness of the strands isnot materially affected by the presence of the adhesive. The adhesiveitself dries with an irregular surface. The strands are stiffened some-5 what bythe adhesive.

After the filtering unit has been formed either with or without anadhesive, a viscous substance, such as oil, is sprayed thereon or theunit is immersed in a bath of the viscous substance until 1 the strandsare thoroughly impregnated and a permanent coating is formed. The excessis allowed to drain off.

Any of the ordinary viscous substances which are commonly used forcoating filtering masses may be used. Suitable substances are automobilelubricating oil, paraffln, lard oil, castor oil, petroiatum, glycerinand wax. Petrolaturn, parafiln, wax and other normally solid ornear-solid, substances should be heated to reduce their vis- 2 cosityand the filtering mass may be immersed therein. Upon cooling a tackycoating remains which is quite suitable for the purpose. The oilcarrying capacity of the strands of this invention is considerablygreater than that of materials which have been used heretofore, such assteel wool and crimped copper strands under similar conditions of voidsproportion or air retriction. With a preferred type of strand, that is,a basswood strand about 0.012 by 0.640 inch transverse section, andautomobile lubricatingbil, the Wood carries somewhat more than its ownweight of oil. In specific examples, using strands of the abovetransverse dimensions, copper strands aggregating 1317 lineal feet inlength (weight 183 grams) carried 34.7 grams of oil, or about .026 gramper iineal foot while wood strands aggregating 1102 lineal feet inlength (weight 28.08 grams) carried 41.92 grams of oil, or about .038gram per lineal foot. Wood strands, therefore, carry about fifty percentmore oil than do metal strands of the same dimensions.

As stated heretofore, the filtering mass of this invention possessesdesirable properties. A primary advantage is the provision of prolongedhigh filtering efficiency. The substantially fiat sides of the differentstrands are practically all disposed in different planes'so that eachimparts a different component of direction to the passing gas or air.The combination of this characteristic and the roughness of the strandssurfaces result in the air or gas being subjected to a thoroughmechanical scrubbing as it passes through the mass. In addition, thecontinued deflection of the gas sets up eddy currents and the dust and.dirt settle out more readilyunder such conditions. The high oil-carryingcapacity is due to the increased adherence caused by the surfaceroughness and porosity of the strands and the .0 presence of projectionsl3 and hairlike particles M, The increased adherence creates aresistance to the action of the air or gas stream in carrying away theoil with use with the result that the oil retention is also high. 5

In addition, there is actual absorption of oil into the wood becausenumerous cell cavities I! are exposed in its surface and the oil has theproperty of penetrating into them. As stated heretofore, the adhesiveforms only a discontinu- 10 ous coating upon the strands, leaving aconsiderable proportion of their surfaces exposed. The oil follows thepores and permeates the wood completely. The cells become impregnatedand act as reservoirs for the replenishment of oil at 16 subjected to athe surface as thelatter becomes depleted. As the oil is carried away bythe air or is taken up and absorbed by the dust and dirt which isentrapped by it at least part of the oil within the cells migrates tothe surfaces by capillary action. Some sort of equilibrium is apparentlymaintained between the quantity of absorbed oil and the quantity of oilcarried upon the surface. As a result, an adequate coating of oil ismaintained for prolonged periods upon the strands. The oil carrying andretaining powers of the strands are not materially aii'ected by thepresence of the adhesive. Because of the characteristics described highinitial filtering efiiciency is obtained and is maintained over longperiods of use. Such charaeteristics are lacking in the non-porous,smoothaurfaced and/or round strands used heretofore and as a result, forcomparable air-restriction conditions, their initial filteringefiiciency is less and the efficiency decreases more rapidly with use.

Filtering emciency. in addition to being dependent upon the physicalcharacter of the filtering mass, is proportional to the flow restrictionoffered per unit volume (or inversely proportional to the void space perunit volume) and to the size of the filter. In the case of automobileair cleaners. space requirements usually determine their size and it isfrequently necessary to provide emciency by the flow restriction ordensity. This, however, may not exceed an allowable maximum, orexcessive restriction will be experienced. In order to meet specificconditions and still maintain uniform high emciency. my filtering massmay be packed so as to weigh from 1 to 8 pounds per cubic foot, basedupon the weight of the wood strands alone. with the oil coating theweight of the mass is approximately 3 to 20 pounds per cubic foot and ifit is bonded together by a sodium silicate adhesive the weight is about4 to 36 pounds per cubic foot. The preferred densities are approximately2 to 5 pounds per cubic foot for the wood strands alone, 4 to 12 poundsfor strands with an oil coating and 7 to 22 pounds for adhesive-bondedstrands with an oil coating. These densities conform. to a voidproportion of from 6'7 to 94% for the contemplated range and from about80 to 92% for the preferred range, based upon the presence of the woodstrands alone. With the adhesive and oil present, the contemplated rangeis about 45 to 90% voids and the preferred rangeis about 65 to 87%voids. These figures are based upon basswood strands and the use ofdifi'erent species of wood of course, results in slighthrdiiferent'figures; Suchflexibility with respect to density ofpackingmakes it possible to predetermine the optimum void size andobtain substantially uniform effectiveness under varying sizelimitations.

Figs. 4 and 5 show a cylindrical filtering unit 2. in whichthe strands2| are packed together into an intertangled mass which may be maintainedin fixed relation by means of the adhesive. As stated heretofore, themajor transverse dimension of each strand is disposed differently fromthat of practically every other strand and because of this heterogeneousarrangementthe fiat surfaces of each strand deflect the oncoming airstream ina difierent direction. The air is thus brought into frictionalcontact with a'maximum surface area of the oil treated strands and isthorough mechanical scrubbing action.

In the construction shown in Figs. 6 and 'l the formed mass of filteringmaterial 2| is placed between concentric cylindrical wire mesh facingmembers 21 and 2|. The facings may also be of perforated metal or othersuitable foraminous material. The top and bottom of the mass are coveredby discs 28v and SI respectively of covering material, such as metal.suitably fireproofed :5 paper, asbestos paper. asbestos cement, etc.,which may be united to the mass by means of an adhesive.

The unit comprising mass 2!, screen facings l1 and 28, and coveringsheets is and Ill may be mounted in an air cleaner body as shown inFigs.

6 and 7. The bottom of the unit rests upon annular retaining member 3|which has bracket 32 extending diametrically between and connecting twoopposite sides thereof. A circular plate 33 is fitted over the top ofthe filtering unit and clamped to a bracket 32 by means of a bolt II anda wing nut 35. An annular member is connected to the bottom side ofretaining member 3|, as by spot-welding. This member curves 80downwardly into the form of a cylindrical outlet 81 which is adapted tobe connected to the intake of a carburetor. The inspired air is drawnradiallythroughthe filteringunitanddlscharged axially through outlet 31.

n The filtering unit shown in Figs. 4 and 5 is adapted to be installedin a cleaner body similar to that shown in Figs. 6 and 7.

Fig. 8 shows a modification of the cleaner unit in which the exteriorscreen facing is sinu- 30 ated forming spaces or air pockets 4i betweenit and the exterior surface of the filtering mass 42. The usual interiorscreen facing 43 is provided. Spaces ll serve to hold quantities of dustand dirt, and permit more uniform distribution of the 35 passing airover the exterior area of filtering mass 42. This arrangement alsodecreases the restriction offered by the exterior screen facing.

Fig. 9 shows an arrangement which advantages in most application andparticularly so under conditions where coarse dust and dirt particlesare encountered. The filtering mass is in two sections. one arrangedexternally of the other, and being of lesser density. External screenfacing 45 may be of relatively coarse 46 mesh. Annular section 46 offiltering mass is arranged within screen facing 45 and is of relativelyless density. For example, section 43 may have a weight of 2 pounds percubic foot, based upon the weight of the wood strands alone.Intermediate partition 41 of wire mesh of some-' what closer mesh thanthat of facing 45 is arranged within filtering mass 46. Arranged in-1teriorly of partition 41 is a section 48 of filtering mass which is ofsomewhat greater density than 55 that of section 46. For example. thewood strands in section 48 may be packed to a weight of 2% pounds percubic foot. An interior screen facing 49 is provided which may be ofsomewhat smaller mesh than is partition 41. In this arrangement theincoming air meets the less dense filtering mass first and has thelarger particles of solids removed in the larger i'fit'erstices ,ofsection 48. The particles are distributed substantially uniformlythroughout the 05 volume of the section. The smaller particles areremoved by section 48 and are likewise distributed substantiallyuniformly throughout the volume of the section. In this manner all partsof the filtering mass are utilized in the dirt and dust removaloperation and the maximum service is obtained.Ifafilteringmassisusedwhichistoo dense for the character of solids inthe air, the large particles are removed at the external surface of theM the interstices become choked,

and the fiow resistance becomes excessive. Under such conditions the airstream may also form enlarged channels through the mass which have nofiltering eifect, with the result that there is practically no filteringfunction.

The invention is not limited to the annular type units described andillustrated heretofore, but may be employed in units of fiat and allother shapes. It may be used in connection with ventilators or in anyother installation, domestic, commercial or industrial, where air or gasfiltration is desired. Where large areas of filtering mass are presentedto the air stream, the thickness'may be whatever is desired but inautomobile air cleaners, where the filtering area must necessarily belimited, it is preferred not to reduce the thickness to less than oneinch.

The removal and replacement of filtering units is very simplyaccomplished by unscrewing wing nut 35 and removing top plate 33, afterwhich the filtering unit may be removed and replaced freely. Theinexpensive character of my improved filtering unit is such that themotorist is quite likely to dispose of it when it has become used anddirty and replace it with a new one rather than to go to the trouble ofcleaning and re-oiling it. In this way it is proposed to provide amarket for units ofthis character such that they may be sold at fillingstations, where the used unit will be removed and the new one installedwithout any effort or trouble upon the part of the motorist.

However, the treated wood strands possess sufficient strength towithstand continued use and units that have become dirty with use may becleaned and re-oiled and re-used repeatedly. If fragments of fiberoccasionally break of! and pass into the engine, the wood merely burnsand is consumed and the quantity of adhesive, which remains as a finepowder, is insignificant. If an organic glue is used, it is consumed,also.

I claim:

1. A gas filtering body comprising a shaped mass of intertangled,elongated wood strands, said strands being angular in transverse sectionand having highly porous, irregular surfaces with a substantial amountof jagged portions and hairlike fringes of body material projectingtherefrom, said strands being bonded together in substantially fixedform and relation by an adhesive, said adhesive forming discontinuouscoatings upon said strands.

2. A gas filtering body comprising a shaped mass of intertangled,elongated wood strands, said strands being angular in transverse sectionand having highly porous, irregular surfaces with a substantial amountof jagged portions and hairlike fringes of body material projectingtherefrom, said strands being bonded together in substantially fixedform and relation by an adhesive, said adhesive forming discontinuouscoatings upon said strands, said strands being impregnated and coatedwith a viscous substance.

3. A gas filtering body comprising a shaped mass of intertangled,elongated wood strands. said strands being angular in transverse sectionand having hi hly porous, irregular surfaces with a substantial amountof jagged portions 5 and hairlike fringes of body material projectingtherefrom, said strands being bonded together in substantially fixedform and relation by an adhesive comprising sodium silicate, saidadhesive forming discontinuous coatings upon said 10 strands.

4. A filtering body for removing solids from a gas stream comprising ashaped mass of intertangled, elongated strands of highly porous wood.said strands being of substantially predetermined in shape anddimensions and having rough, porous surfaces, said strands being bondedtogether in substantially fixed form and relation by an adhesive, saidadhesive forming incomplete coatings upon said strands, said strandsbeing im- 20 pregnated and coated with a viscous substance.

5. A gas filtering body comprising a shaped mass of intertangled,elongated wood strands, said strands being angular in transverse sectionand having hi hly porous, irregular surfaces with a substantial amountof jagged portions and hairlike fringes of body material projectingtherefrom, said strands being bonded together in substantially fixedform and relation by an adhesive, said adhesive forming discontinuouscoat- 80 ings upon said strands, said mass weighing ap-, proximately 7to 22 pounds per cubic foot.

6. A filtering body for removing solids from a gas stream comprising ashaped mass of intertangled elongated strands, said strands beingangular in transverse section and having highly porous, irregularsurfaces with a substantial amount of jagged portions and hairlikefringes of the body material projecting therefrom, said strands beingbonded together in substantially fixed form and relation by an adhesive,said adhesive forming incomplete coatings upon said strands, saidstrands being impregnated and coated with a viscous substance, said bodybeing encased in a foraminous supporting frame and having its shortdimension aligned with the path of the gas stream.

7. A gas filtering body comprising a mass of intertangled, elongatedwood strands, said strands being bonded togetherin substantially l0fixed form and relation by an adhesive, said adhesive formingdiscontinuous coatings upon said strands.

8. An air cleaner for internal combustion engines comprising a framehaving radial inlet and axial outlet, a shaped body of filteringmaterial in said frame, said material comprising a mass of intertangled,elongated wood' strands, said strands being bonded together insubstantially fixed form and relation by an adhesive said adhesiveforming discontinuous coatings upon said strands.

HOWARD F. WEISS.

